A researcher posing as a 15-year-old football player called 244 health food stores across the United States and asked if they would sell him protein supplements to give him larger muscles. More than two-thirds of sales attendants at the health food stores recommended that he buy the protein supplement, creatine (Pediatrics, published online Feb. 2017).

It is incredible that people with no training in medicine or nutrition are giving advice about food supplements to young kids. The American Academy of Pediatrics and the American College of Sports Medicine recommend that people under 18 should not use any protein supplements. The label on many creatine containers says that they are not recommended for minors. A well-balanced diet will provide all the protein and other nutrients an athlete needs.

The entire "over-the-counter" food supplement industry is unregulated regarding efficacy or toxicity. In 2010, Consumer Reports tested 15 protein powders and drinks and found that some of the products contained arsenic, lead, cadmium and mercury.

What is Creatine?
Creatine is a naturally occurring organic compound that is made by your kidneys, pancreas and liver. It is also found in meat, chicken and fish. Many kids and adult athletes buy and take creatine as a powder, liquid or pill in the hope that it will help them grow larger muscles when they lift heavy weights.

Does a Very High Protein Diet Grow Larger Muscles?
Eating lots of high protein foods does not help athletes grow muscles larger than when they take in moderate amounts of protein (Journal of Sports Sciences, 2004;22(1)), even though athletes will absorb more protein on the high-protein diet (Journal of Applied Physiology, Aug 1992;73 (2): 767–75). However, taking in less protein than you need (approximately 0.7g/kg/day) will cause loss of muscle size (Journal of the American Medical Association, Jan 2012;307(1):47–55).

Several studies show that an athlete will gain maximum muscle growth from taking in up to 1.8 g/kg/day of protein (Journal of Applied Physiology, 1985;73 (5): 1986–95; Journal of Sports Sciences, 2004;22(1)). A male who weighs 180-pounds (82 kilograms) will gain maximal muscle growth on 147 grams of protein per day (82 kg x 1.8g/kg/day). That is 16 percent of his total food intake of 3700 calories per day. This means that he can get half of his maximal protein benefit by eating 10 ounces of steak, chicken or fish. No protein supplement offers more healthful protein than what you can get in the food that you eat.

How Much Protein Do You Need?
The average adult can achieve the recommended protein intake of 46 grams of protein a day for women and 56 grams for men just by eating corn and beans. Three cups of beans contain 56 grams of protein. A cup of chopped chicken contains 44 grams of protein and a cup of yogurt contains 20 grams. The average North American man takes in 100 grams of protein a day (analysis of the 2007-2010 National Health and Nutrition Examination Survey). The only groups with reported low protein intake were teenage girls and some men and women over 70.

Side Effects of a Diet Very High in Protein
High doses of creatine have been reported to cause dehydration and kidney and liver damage. Very-high-protein diets are associated with increased risk for heart attacks (BMJ, June 26, 2012;344:e4026). Elite body builders and competitive athletes in sports requiring great strength are at increased risk for dying from heart attacks and diabetes (J of Urology, April 2016;195(Supplement):e633). I believe that the extra protein these athletes tend to eat may explain part of that risk.

A high-protein diet is defined as more than 20 percent of daily calories being supplied by protein. Excess protein makes cells multiply faster to increase risk for cancer. Valter Longo at the University of Southern California in Los Angeles showed that people who eat a high-protein diet between ages 50 and 65 were four times more likely to die of cancer than those who consumed less protein (Cell Metabolism, March 4, 2014;19(3):407–417). High protein diets also raise blood levels of insulin-like growth factor-1 (IGF-1) and increase DNA damage to increase risk for both diabetes and cancers. Lower-protein diets are associated with reduced IGF-1, cancer and diabetes and a longer life span (Cell Metabolism, March 4, 2014;19(3):418–430). That study concluded that plant-based proteins are associated with lower mortality than animal-derived proteins.

A major benefit of losing excess weight is that it causes cells to respond better to insulin and blood sugar levels to drop to normal to reduce a person's chances of becoming diabetic and suffering a heart attack. However, when an animal loses weight on a high-protein diet, its sensitivity to insulin does not improve (Cell Rep, 2016 Oct 11;17(3):849-861).

My Recommendations
• A very high intake of protein has not been shown to grow larger or stronger muscles.
• Very high protein diets have been reported to increase risk for diabetes and cancers.
• A person can get all the protein he needs for muscle and strength growth from eating moderate amounts of protein-rich foods.

About the Author: Gabe Mirkin, MD

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D., brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. The Dr. Mirkin Show, his call-in show on fitness and health, was syndicated in more than 120 cities.
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